Method and tube for lining a high pressure pipe

ABSTRACT

The invention relates to a method for lining a high pressure pipe with a tube made from interlocking, high-tensile high performance fibers, with a plastic coating applied thereto, whereby the high performance fibers are arranged in an interwoven structure and introduced into the pipe in a state of mobility relative to each other. The introduced meshing is then pressed against the inner wall of the pipe by altering the geometrical arrangement of the high performance fibers with relation to each other and then fixed by the mutual arrangement of the high performance fibers adopted after the laying thereof. The invention further relates to a tube for lining a high-pressure pipe comprising interlocking, high-tensile high performance fibers and a plastic coating applied thereto, embodied such that the high performance fibers are arranged within the structure as a mesh and the angle of the high performance fibers may be altered in relation to the perpendicular to the tube axis before the lining, such that an enlarging of the tube in a radial direction is possible.

[0001] The invention relates to a method according to the preamble of claim 1 as well as a tube according to the preamble of claim 6.

[0002] High-pressure pipes transport fluid media at a pressure in the range of more than 1 bar. The pipes must therefore withstand correspondingly high forces and be of adequate dimensions. For the tubes, therefore, so-called high-performance fibres are used which have a high tearing strength and are relatively high-tensile. From the viewpoint of increasing the strength, these fibres are most effective when they run perpendicular to the longitudinal axis of the pipe or tube. The fabrics of the known tubes are so configured that they consist of warp and weft threads which run in the longitudinal direction of the tube or respectively perpendicular to same. These tubes, however, have only low tensibility in a radial direction. This tensibility is not sufficient, however, to compensate for production tolerances of the pipes and the tubes. Since maximum tolerances of the pipes and the tubes of roughly 3% in each case have to be taken into account, a tube of this type should have a tensibility of not less than 6%.

[0003] The previous renovation tubes for high-pressure pipes have, as mentioned above, a fabric formed from warp and weft threads, the warp threads running in the longitudinal direction of the pipe.

[0004] The object of the present invention, therefore, is to give a method for lining a high-pressure pipe with a tube formed from interlocking, high-tensile high-performance fibres and a plastics coating applied to said fibres, as well as a tube of this type, which despite high strength in a radial direction and also in an axial direction permit a maximum radial enlargement of the tube to at least 3% above the nominal diameter of the pipe.

[0005] This object is accomplished according to the invention by the features of claim 1 in respect of the method and by the features of claim 6 in respect of the tube. Advantageous developments of the method or tube according to the invention arise from the respective subordinate claims.

[0006] Since the high-performance fibres are arranged in a braided structure and are introduced into the pipe in a state of mobility relative to one another, and since the introduced meshing is laid against the inner wall of the pipe by altering the geometrical arrangement of the high-performance fibres in relation to one another and these fibres are then fixed in their relative position assumed after they have been laid, the tube can, as it is laid against the inner wall of the pipe, be so enlarged in a radial direction practically without any force, that production tolerances or otherwise caused fluctuations of the inside diameter of the pipe can be compensated without the high-performance fibres themselves being stretched.

[0007] The invention is explained in greater detail below with the aid of an embodiment represented in the figures. These show:

[0008]FIG. 1 a detail of a non-coated fabric in the form of a meshing formed from fibres crossed alternately over and under one another before being introduced into the pipe, and

[0009]FIG. 2 the arrangement of the fibres of the meshing according to FIG. 1 after being laid against the inner wall of the pipe and being fixed by the plastics coating.

[0010]FIG. 1 shows the meshing before it is introduced into the pipe and fixed to the inner wall of same. The mutual crossing angles of the high-performance fibres 1 and their angle in relation to the perpendicular to the tube axis are insignificant as long as the high-performance fibres 1 are so mobile relative to one another that they can be brought without any tension into the orientation shown in FIG. 2. This orientation arises after the meshing has been introduced into the pipe and laid against its inner wall.

[0011] The meshing can be introduced into the pipe for example by inversion or by simple pulling-in. In particular in the case of inversion it is necessary for the meshing to be already provided with a coating which is impermeable by the medium used for the inversion, usually air. This coating must be so elastic that it still permits adequate movement of the high-performance fibres 1 relative to one another, in order to be able to lay the meshing practically tension-free against the inner wall of a pipe which has an inside diameter lying within the tolerance range. After being laid against the inner wall, the meshing is fixed. If initially only the meshing without any coating has been introduced into the pipe, it is then fixed by the application of a subsequently hardening plastics material. If, on the other hand, the meshing has been introduced already in the coated state, the fixing can be carried out in such a way that the already present coating is subsequently hardened, or an additional, subsequently hardening, coating is applied.

[0012] In the tube, introduced into the pipe and laid against its inner wall, the high-tensile fibres should be at as small an angle as possible in relation to the perpendicular to the tube axis or the longitudinal axis of the pipe, which is indicated by an arrow, and this angle, depending on the admissible production tolerances of the pipe, makes possible a maximum enlargement of preferably in the range between 3% and 10% above the nominal diameter of the pipe, until the smallest possible angle in relation to the perpendicular of the tube is reached (roughly 10° to 35° depending on the type of braiding). This angle should be as small as possible for the reason that when there is internal pressure in the pipe, radial forces arise which are best absorbed by fibres running perpendicularly with respect to the tube axis, i.e. in a circumferential direction.

[0013] For coating the meshing before introducing it into the pipe it is advantageous if the meshing formed from fibres 1 is interspersed by so-called rib threads 2 (longitudinal threads which run parallel to the tube axis). During the coating process, these rib threads 2 are held at a specific length and are intended to absorb in an axial direction the forces acting on the meshing. They thus prevent the angle of the threads 1 in relation to the perpendicular to the tube axis from exceeding a specific value. Then only a further slight relative movement between the high-performance fibres 1 is necessary to lay the coated meshing against the inner wall of the pipe. The rib threads 2 can also have different mechanical properties from the fibres 1.

[0014] As suitable high-performance fibres to be used as fibres 1 in the meshing can be recommended e.g. glass fibres, aramid fibres, UHM (ultra-high molecular) PE fibres, carbon fibres, PBO (poly(p-phenylene-2,6-benzobisoxazole)) fibres or steel fibres.

[0015] The meshing can consist of yarns which are formed from the high-performance fibres. Individual yarns, or a plurality of yarns which run parallel or are twisted (braids) can be used here. Furthermore, rovings can be used. It is also possible to braid bands or belts woven or plaited from yarns.

[0016] The meshing can have braiding pattern 1 or braiding pattern 2. In the case of braiding pattern 1, a fibre (or respectively yarn, roving, yarn bundle, band or belt) can be guided respectively on the one side only over one of the fibres crossing it and on the other side only over the subsequent fibre crossing it, whilst in the case of braiding pattern 2, the fibre is guided on the one side respectively over two successive fibres and on the other side over the two next successive fibres. 

1. Method of lining a high-pressure pipe with a tube formed from interlocking, high-tensile high-performance fibres (1) and a plastics coating applied to said fibres, characterised in that the high-performance fibres (1) are arranged in a braided structure and are introduced into the pipe in a state of mobility relative to one another, and in that the introduced meshing is laid against the inner wall of the pipe by altering the geometrical arrangement of the high-performance fibres in relation to one another, and is then fixed with the mutual arrangement of the high-performance fibres (1) which has been assumed after they have been laid.
 2. Method according to claim 1, characterised in that the meshing is laid by reducing the angle of the high-performance fibres (1) in relation to the perpendicular to the tube axis.
 3. Method according to claim 1 or claim 2, characterised in that the high-performance fibres (1) are laid free of internal stress against the inner wall of the pipe.
 4. Method according to one of claims 1 to 3, characterised in that the meshing is introduced uncoated into the pipe, and to fix the high-performance fibres (1), the coating is applied to the high-performance fibres (1) in the pipe.
 5. Method according to one of claims 1 to 3, characterised in that the meshing is introduced into the pipe with a coating which permits relative movement of the high-performance fibres (1) in respect of one another, and in that, to fix the high-performance fibres (1), the coating is hardened or supplemented by an additional coating.
 6. Tube for lining a high-pressure pipe, which has interlocking, high-tensile high-performance fibres (1) and a plastics coating applied to same, characterised in that the high-performance fibres (1) are arranged in a braided structure and the angle of the high-performance fibres (1) in relation to the perpendicular to the tube axis before lining can be so altered, that enlargement of the tube in a radial direction is possible.
 7. Tube according to claim 6, characterised in that the high-performance fibres (1) intersect at an acute angle, enclosing the perpendicular to the tube axis.
 8. Tube according to claim 6 or 7, characterised in that the angle of the high-performance fibres (1) in relation to the perpendicular to the tube axis in the lining state is as small as possible.
 9. Tube according to one of claims 6 to 8, characterised in that the high-performance fibres (1) are free of internal stress in the lining state.
 10. Tube according to one of claims 6 to 9, characterised in that the angles of the interlocking high-performance fibres (1) are symmetrical in relation to the perpendicular to the tube axis.
 11. Tube according to one of claims 6 to 10, characterised in that the meshing permits an enlargement of the tube in a radial direction in the range between roughly 3% and 10% above the nominal diameter of the pipe.
 12. Tube according to one of claims 6 to 11, characterised in that the high-performance fibres (1) are glass fibres, aramid fibres, UHMPE fibres, carbon fibres, PBO fibres or steel fibres.
 13. Tube according to one of claims 6 to 12, characterised in that the fabric has additional fibres (2) in the axial direction of the tube.
 14. Tube according to one of claims 6 to 13, characterised in that the meshing is formed from individual yarns, a plurality of parallel or twisted yarns or rovings.
 15. Tube according to one of claims 6 to 13, characterised in that the meshing is formed from bands or belts woven or braided from yarns.
 16. Tube according to one of claims 6 to 15, characterised in that the meshing has weave pattern 1 or weave pattern
 2. 